3 * If the instructions below seem overwhelming, note that it should be possible to do a lot of this course using only demonstration versions of these languages [[that run in your web browser|browser]].

103 * One of Intel's i386, i486, i586, i686 architectures. These are collectively known as "x86" or "IA-32" or sometimes just "32-bit".

104 * Intel or AMD's x86\_64 architecture. This is also called "x64" or "amd64" or "IA-64" or sometimes just "64-bit". (Note that these *aren't* "x86" machines, even though "x86\_64" starts with those letters.)

105 * ARM or some other architecture. These are generally lower-powered machines, like iPads. Some of the software we're proposing *might* in principle be capable of running on such machines, but installers don't seem to be available. We'll assume you have access to an x86 or x86\_64 machine.

170 Racket and Chicken stand to Scheme in something like the relation Firefox stands to HTML. They are two programs (or platforms) among others for working with the Scheme language; and many of those programs (or web browsers) permit different extensions, have small variations, and so on.

172 Racket has several components. The two most visible components for us are a command-line interpreter named "racket" and a teaching-friendly editor/front-end named "DrRacket". You will probably be working primarily or wholly in the latter.

173 <!-- "racket" used to be mzscheme, "DrRacket" used to be DrScheme -->

201 Here are the exact steps I just verified worked. Note that I *first installed the Haskell Platform*, described further down this page; that installed some developer tools that were needed to build and install Chicken. If you don't know how to open a Terminal, move between directories, copy / rename / delete files and so on, then you're probably best off not doing this. You could break something.

203 1. Go to <http://code.call-cc.org>, and click the "Source code" link near the top. Current version is 4.9.0.1, released November 2014. This should fetch a file to your download folder, and will probably automatically unpack that file into a folder, "chicken-4.9.0.1". Click on that folder and press command-C / Copy, then open a Terminal.

204 2. In the terminal type `cd` followed by a space, then press command-V / Paste. Then press enter. This will move your session into the folder you just downloaded. <!-- Type `less README` and read that file. -->

207 The options starting with `XCODE_` are to tell the Chicken build scripts that I've got the developer tools installed in my main system, rather than as part of Xcode. (That's where the Haskell Platform installer put them.) Continuing:

210 5. If it finishes with no errors, then type `make PLATFORM=macosx XCODE_TOOL_PATH=/usr/bin PREFIX=$HOME install`. This will install Chicken in your user home directory.

211 6. At this point you can type `which chicken`. It should give you an answer of "/Users/yourname/bin/chicken".

212 7. In your terminal, type `chicken-install r7rs datatype matchable monad`. <!-- with "-sudo" if you installed chicken in /usr/local --> This will download, build, and install a few extensions (Chicken calls them "eggs") relevant to ideas we'll be working with in this course.

318 The people in charge of OCaml (they're at the French research institute INRIA) have stopped making pre-built packages for Mac OS X. One option you have is to use their package for a slightly older version of OCaml, 4.01.1 from Sept. 2013. You can find that as a "Precompiled binary for Mac OS X" on [this page](http://ocaml.org/releases/4.01.0.html). If, when you attempt to install this package, you get an error about its being from an "unidentified developer," you need to control-click on the `ocaml.pkg` file and select "Open", then when the warning box appears again, this time there will be an "Open" button that you can click. Then you can continue running the Installer.

422 Like Scheme, Haskell has a couple of different implementations. The dominant one, and the one we recommend you install, is called [GHC](https://wiki.haskell.org/GHC), short for "Glasgow Haskell Compiler". To install this on your machine, there are a couple of different strategies. It's helpful to understand some lingo as you begin this process:

424 * As mentioned, **GHC** is the main Haskell engine or compiler you'll be installing. The current version is 7.8.4, from December 2014.

425 * **gcc** and **llvm/clang** and **Xcode** and **MinGW** are names for other compilers on various systems. Oftentimes these will be used during the installation process to get GHC up and running. Some of the strategies described below will help you install these if they're not already on your machine.

426 * **alex** and **happy** and **haddock** are names of various Haskell helper programs that GHC uses to get up and running.

427 * **cabal** is a "package manager" for Haskell. It allows you to install libraries or extensions that other people have built. (Usually those are published at the [Hackage](https://hackage.haskell.org) Package Database.) Some of these are experimental and may not always work; others are quite fundamental and are almost de facto parts of what people expect in a Haskell system.

428 * The **[Haskell Platform](https://www.haskell.org/platform/contents.html)** is a standard bundle that includes a specific version of GHC, plus specific versions of some of the most popular libraries or extensions. This is updated once or twice a year. The current version is 2014.2.0.0, from August 2014. It includes GHC version 7.8.3.

432 * Go to <https://www.haskell.org/platform/windows.html> and follow the instructions. It looks like this process will automatically install the MinGW compiler needed to get this build of Haskell running on Windows.

436 * Go to <https://www.haskell.org/platform/mac.html> and follow the instructions. This requires Mac OS X 10.6 / Snow Leopard or later; but there is a link to an earlier version of the Haskell Platform, that's built for Mac OS X 10.5 / Leopard. During the installation, you may be prompted to install "the command line developer tools"; this is a portion of what Apple bundles together with Xcode (mentioned above on this page). The installer will take care of getting these for you if you give it permission.

472 If any of the instructions above don't work, then you can try alternative instructions for [Mac](http://new-www.haskell.org/downloads/osx) or [Windows](http://new-www.haskell.org/downloads/windows) or [Ubuntu](http://new-www.haskell.org/downloads/linux). Note that this method doesn't install all the extensions that are part of the Haskell Platform, but only the core pieces of GHC. You can use Cabal to download and manage any extra extensions you turn out to need, down the road.

488 After issuing the relevant `echo` command, I exited the Terminal and started a new Terminal session. Now if I type `echo $PATH` I should see the directory I just added in the list. Now I can contine setting up Cabal. I type: